1. Field of the Invention
The present invention relates generally to electric power supply and generation systems and, more particularly, to the management and control of communications to and from utility service points.
2. Description of Related Art
The increased awareness of the impact of carbon emissions from the use of fossil-fueled electric generation combined with the increased cost of producing peak power during high load conditions have increased the need for alternative solutions utilizing load control as a mechanism to defer, or in some cases eliminate, the need for deploying additional generation capacity by electric utilities. Existing electric utilities are pressed for methods to reduce, defer, or eliminate the need for construction of fossil-fuel based electricity generation. Today, a patchwork of systems exist to implement demand response load management programs (e.g., typically referred to as “demand side management” or “DSM”), whereby various radio subsystems in various frequency bands utilize “one-way” transmit only methods of communication. Under these programs, radio frequency (RF) controlled relay switches are typically attached to a customer's air conditioner, water heater, or pool pump. A blanket command is sent out to a specific geographic area such that all receiving units within the range of the transmitting station (e.g., typically a paging network) are turned off during peak hours at the election of the power utility. After a period of time when the peak load has passed, a second blanket command is sent to turn on those devices that were previously turned off.
In addition to DSM, some electric utilities utilize tele-metering for the express purpose of reporting energy usage. However, no techniques exist for calculating power consumption and/or greenhouse gas emissions (e.g., carbon gas emissions, sulfur dioxide (SO2) gas emissions, and/or nitrogen dioxide (NO2) emissions), and reporting the state of a particular power consuming device or set of power consuming devices operating under the control of a two-way positive control load management policy. In particular, one way wireless communication devices have been utilized in DSM systems to de-activate electrical appliances, such as heating, ventilation, and air-conditioning (HVAC) units, water heaters, pool pumps, and lighting, from an existing electrical supplier or distribution partner's network. These devices have typically been used in combination with wireless paging receivers that receive “on” and “off” commands from a paging transmitter. Additionally, the one-way devices are typically connected to a serving electrical supplier's control center via landline trunks or, in some cases, microwave transmission to the paging transmitter. The customers subscribing to the DSM program receive a discount for allowing the serving electrical supplier (utility) to connect to their electrical appliances and deactivate those appliances temporarily during high energy usage periods.
Power meters and metering technology are important capabilities of the power industry and are used in connection with existing DSM systems. Power meters provide the critical use information necessary for the utility to bill its customers. Conventional power meters use simple technology to detect the amount of electricity used by a customer service point at which the power meter is installed. Thus, the information obtained from a conventional meter is typically the total amount of electricity used by a service point (e.g., residence or business) to date. Meter reading is still typically performed manually on a periodic basis (e.g., monthly), such that a power utility worker physically travels to each assigned meter to read it. The usage or consumption information read from the meter is typically input manually into a handheld data storage device and the data from the storage device is transferred into the utility's billing system. On-site meter reading has a number of disadvantages, including (a) dangers to utility personnel from uncontrolled pets or other animals, (b) physical difficulties gaining access to the meter, (c) weather, and (d) time and cost associated with traveling to a service point, which may be in a remote area.
To overcome many of the problems associated with manual, on-site meter reading, some utilities have begun to use Automatic Meter Reading (AMR) technology that allows utilities to remotely read meters without having to physically view the meter. FIG. 1 illustrates differences between manual meter reading and AMR in an exemplary utility service area. In accordance with AMR technology, advanced meters transmit meter data wirelessly, either automatically or responsive to wireless wake-up polls received from a wireless controller in the general vicinity of the meter. Therefore, advanced meters may be read by workers equipped with wireless data collection devices who simply walk or drive past the service points having advanced meters. When an advanced meter requires a wake-up poll in order to transmit its data, the controller issuing the poll may be included in a wireless data collection device. Because utility personnel do not need to physically view each meter, AMR substantially reduces meter reading time and provides a significant reduction in labor costs, as well as improves the safety of utility personnel. However, because AMR typically requires a utility worker to be in the proximity of each service point in order to read the service point's meter, the labor costs associated with implementing AMR are still substantial.
To overcome the disadvantages of AMR, Advanced Metering or Advanced Metering Infrastructure (AMI) technology was developed. AMI technology allows power utilities to remotely read meters using new communications technology, such as the Internet, power line communications, and wide area wireless technology. AMI technology also allows the use of other remote functionality, such as remote disconnection of power to a service point. The advanced meters used with AMI technology are sometimes referred to as “smart meters.”
Thus, AMI provides two-way communication between a utility and the smart meters distributed throughout the utility's service area. Some of the key features of AMI technology include:
Communication “on demand”—Communication between the utility and the smart meter may occur at any time and may be two-way. Communication between the utility and conventional meters typically occurs just once a month and is one-way from the meter to the utility.
Rapid measurement and transmittal of usage data—The amount of power used can be measured much more frequently than the monthly measurement of conventional metering cycles. In addition, these measurements can be transmitted to the utility more frequently.
Information to the utility—Meter data that is sent to the utility may be used to glean additional information about a customer (e.g., power usage patterns), and aggregated data can be used for optimization and planning.
Feedback to the customer—AMI technology enables utilities to provide detailed information about energy usage to their customers, which in turn enables the customers to make intelligent changes to the way they consume electricity.
FIG. 2 illustrates, in block diagram form, how AMI technology works generally for a group of service points 201-205. The utility 207 communicates to smart meters 211-215 at the service points 201-205 using wide area wireless or wired technology. Thus, the utility 207 and all the service points 201-205 in the utility's service area effectively form a wide area network (WAN) 217.
If, in accordance with an AMI protocol, the smart meters 211-215 at all the service points 201-205 are transmitting frequently, there is a risk that all, or at least a substantial number, of the smart meters 211-215 in a utility's service area could transmit at the exact same point in time (i.e., their transmission pulses would be the same) or that such transmissions could overlap and conflict. Depending on the available bandwidth of the WAN's reverse link from the smart meters 211-215 to the utility 207, a substantial number of simultaneous or overlapping transmissions from the smart meters 211-215 can place an inordinate strain on the WAN 217 and cause a data bottleneck, possibly resulting in lost or unacceptably latent (e.g., out-of-date) data. Additionally, depending on the available bandwidth of the WAN's forward link from the utility 207 to the service points 201-205, a transmission bottleneck may also result in the forward direction when the utility 207 attempts to communicate simultaneously or substantially simultaneously with all or substantially all of the smart meters 211-215 in the utility's service area. Such transmission bottlenecks may be exacerbated where the WAN 217 relies upon a public wireless network, such as a cellular network, to implement at least part of the WAN's forward and reverse links, especially after a power outage when the utility 207 and all the smart meters 211-215 attempt to re-synchronize and share current information with one another.
Therefore, a need exists for a system and method for controlling communications between a utility and its service points to reduce the likelihood of data bottlenecks in either the forward or reverse direction.